Vibratory centrifuge



July 11, 1961 T. WIRTH ETAL 2,991,887

. VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 1 INVENTORS.mamas Il {r513 I BY Wz/zer fioaer W n w July 11, 1961 T. WIRTH ETAL2,991,887

VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 2 711/ III/1n 6$0 INVENTORSn Tfiozzzas Mhf/Z July 11, 1961 T. WIRTH ET AL 2,991,887

VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 3 United StatesPatent Office Patented July 11, 1961 Obermenzing, Germany Filed Dec. 12,1957, Ser. No. 702,404

Claims priority, application Germany Dec. 19, 1956 8 Claims. (Cl.210-376) This invention relates to a vibratory centrifuge of the kindhaving a basket which is rotatably mounted in a centrifuge housing andis reciprocated in the direction of its axis of rotation for the purposeof effecting the discharge of the centrifuged solids therefrom.

In known centrifuges of this type, the rotated basket increases indiameter in the direction toward the discharge end thereof, and theperforated wall of the basket is inclined relative to the axis ofrotation at an angle corresponding approximately to the angle of reposeof the material which is to be centrifuged. In order to effect thedischarge of the centrifuged solids from the basket, the latter isreciprocated, by an eccentric, cam or the like acting upon the basketshaft which is mounted for axial sliding. The purpose of such anarrangement is to provide for the discharge of the centrifuged solidswith the least possible damage to the granular structure thereof and tothe perforated wall of the basket because only the component of thecentrifical force which is perpendicular to the basket wall acts to urgethe centrifuged solids against the wall. In order to assure discharge ofthe centrifuged solids, even under conditions of varying viscosity, thecomponent of the centrifical force which acts in the axial direction ofdischarge is reenforced by the parallel component of the impulseresulting from reciprocation of the basket. However, it has been foundthat 'the rate of discharge cannot be satisfactorily adjusted withrespect to the properties of the centrifuged material, even whenprovision is made for varying the amplitude and frequency of thereciprocation of the basket. Thus, the time of dwell of the centrifugedmaterial in the basket is too short for satisfactory dewatering of thecentrifuged material when a material of high fluidity is centrifuged,and supplementary dewatering is then required. On the other hand, whencentrifuging highly viscous materials, the time required for thecentrifuging operation is increased to an undesirable extent because ofthe unnecessarily long dwell time of the material in the centrifugebasket. These disadvantages may be overcome by maintaining a stock ofcentrifuge baskets having different opening sizes, which areinterchanged, as required, for adaptation to the properties orcharacteristics of the material to be centrifuged. However, the initialcost of a vibratory centrifuge is substantially increased by such sparebaskets, and centrifuging operations are slowed down by the timerequired for interchanging baskets.

Accordingly, it is an object of the present invention to provide animproved centrifuge of the described type which, by simple means,permits the achievement of the desired degree of dewatering of thecentrifuged material independent of the properties of the latter.

In accordance with an aspect of the invention, the foregoing object isachieved by providing a centrifuge basket having an open end for,discharge of the centrifuged material therethrough and a wall which iscylindrical at least in a portion of the basket adjacent the oppositeend of the latter, a pusher bottom which is mounted within thecylindrical portion of the basket for rotation with the latter, butindependent of the axial reciprocation of the basket, so that, when thebasket is reciprocated, a relative reciprocation occurs between thebasket and the pusher bottom and the latter acts to progressively 2displace the centrifuged material toward the open end of the basket.

In one embodiment of the invention, the pusherbottom is mounted on ashaft which extends axially into the basket through the open end of thelatter, one end of the shaft being supported by a bearing assemblycarried by the centrifuge housing to permit rotation of theshaft whilepreventing axial movement of the latter, while the other end of theshaft is coupled to the basket for rotation with the latter whilepermitting axial movement of the basket relative to the shaft so thatthe length of the stroke of the relative reciprocation of the basket andpusher bottom is equal to the length of the reciprocating stroke of thebasket.

In a preferred embodiment of the invention, the pusher bottom and thebasket are both axially reciprocated, but in opposite directions, sothat the stroke of the relative reciprocation of the basket and pusherbottom is greater than the reciprocating stroke of the basket, therebyto increase the rate at which the pusher bottom can effect the axialdischarge of centrifuged material from. the basket.

In still another embodiment of the invention, the pusher bottom isincorporated in a reciprocating centrifuge, for example, of the kinddisclosed in U.S. Patent 2,872,045 to Thomas Wirth, Karl-Heinz Nebhuthand Karl Wenger, for Oscillating Centrifuge, wherein a balancing mass ismounted for reciprocation in the direction of the rotational axis of thebasket and the basket and balancing mass are reciprocated in oppositedirections and are elastically coupled to each other to form a dual-massoscillating system, with the pusher bottom being rigidly connected tothe balancing mass for recipro-v cation with the latter relative to thereciprocated basket.

Further, in accordance with an aspect of this invention, the centrifugebasket may be of stepped configuration increasing in diameter toward theopen end thereof with the pusher bottom being installed within theportion of the basket having the smallest diameter, while pusher ringsconnected to the pusher bottom for reciprocation with the latterrelative to the reciprocated basket, are disposed at each step orincrease in diameter of the basket to provide successive impulses formoving the centrifuged material towards the open discharge end of thebasket as such material moves along the basket wall. Such an arrangementis of particular advantage in connection with the dewatering orcentrifuging of materials which are diflicult to filter, such as, forexample, sugar products, citrates and the like, which might becompressed or compacted if subjected only to the action of thereciprocated pusher bottom disposed at the end of the basket remote fromthe open discharge end of the latter.

The above, and other objects, features and advantages of the invention,will be apparent in the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings, forming a part hereof, and wherein:

FIG. 1 is an axial section-a1 view of a vibratory centrifuge embodyingthe present invention;

FIG. 2 is an axial sectional view of a vibratory centrifuge constructedin accordance with another embodiment of the invention;

FIG. 3 is an axial sectional view of a vibratory cent-rifuge constructedin accordance with still another embodiment of this invention;

FIG. 4 is an axial sectional view of a vibratory centrifuge constructedin accordance with still another embodiment of this invention; and 1FIG. 5 is a view similar to that of FIG. 4, but showing still anotherembodiment of the invention. l

Referring to the-drawings in detail, and initially to FIG. 1 thereof, itwill be seen that a vibratory centrifuge embodying the present inventionincludes a centrifuge basket 1 having a cylindrical perforated side wall2 which is covered, at its inner surface by a screen liner 3. The basket1 is open at one end for the discharge of the centrifuged materialtherethrough, and the other end of the centrifuge basket is closed by anend wall 15 having a central hub 16 which is fixedly secured on a basketshaft 17. The shaft 17 is axially slidable, as indicated by the arrows,within a sleeve 19, and the latter is rotatably supported in a bearing20 carried by a transverse partition 21 of a centrifuge housing 4, sothat the centrifuge basket 1 is free to rotate about its central axisand to reciprocate in the direction of that axis relative to the housing4. A suitable conventional drive and reciprocation generator (not shown)is associated with the sleeve 19 and the shaft 17 in order to effectrotation of the basket 1 and axial reciprocation thereof.

The material to be centrifuged is supplied to the basket 1 through theopen end of the latter by way of a feed pipe which is fixed relative tothe housing 4 and extends downwardly and then axially into the open endof the basket. Within the basket 1, the end portion of feed pipe 5 isslidably received in a cylindrical extension 6 of a funnel 7 whichfiairs outwardly and opens in the direction toward the end wall 15 ofthe basket.

In accordance with the present invention, a circular pusher bottom 8having an outer diameter only slightly smaller than the inner diameterof the cylindrical wall 2 of the basket is disposed within the latterbetween the end wall 15 and the funnel 7. The pusher bottom 8 iscentrally mounted on a shaft 9 which is aligned with the axis of thebasket '1 and which passes axially through the funnel 7 and then througha stuffing box or seal 11 in the vent portion of feed pipe 5. The end ofshaft 9 extending out of feed pipe 5 is supported by a bearing assemblycarried by the housing 4 and including a thrust bearing 12 preventingaxial movement of shaft 9 relative to housing 4 and a radial bearing 13accepting the radial loads on the shaft 9. The opposite end of shaft 9extends through pusher bottom 8 and is provided with an end portion 14of square or other non-circular crosssection, which extends into thebasket wall 15 and the hub 16 and is axially slidable in a recess 18 ofcorresponding square or other non-circular cross-section provided in theadjacent end of basket shaft 17. Thus, the cooperating end portion 14 ofshaft 9 and recess 18 of shaft 17 provide an non-rotatable, but axiallyslidable coupling between the basket and the shaft 9, and hence also thepusher bottom 8.

As seen in FIG. 1, the funnel 7 is secured to the pusher bottom 8, forexample, by means of straps 22, so that the periphery of the funnel 7will be spaced axially from the face of pusher member 8 directed towardthe open end of the basket, while the funnel 7 will participate in therotary movement of pusher bottom 8 with basket 1.

During operation of the centrifuge described above with reference toFIG. 1, the basket 1 is rapidly reciprocated in the direction of itsaxis and simultaneously rotated about that axis by suitable actuation ofthe shaft 17 so that material to be centrifuged, upon entering throughthe feed pipe 5, is deposited by the feed funnel 7 against theperipheral portion of the surface of pusher bottom 8 facing toward theopen end of the basket. Since the pusher bottom 8 is held against axialmovement relative to the housing 4, while the basket 1 reciprocates withrespect to the housing, it is apparent that relative axial reciprocationwill occur between the basket and the pusher bottom. During thereciprocating stroke of the basket 1 in the axial direction away fromthe open discharge end thereof,

centrifuged material abutting against the peripheral portion of thepusher bottom will be pushed, by the latter, along the screen liner 3 inthe direction toward the open discharge end of the basket. When thereturn reciprocating stroke of the basket occurs, that is, when thebasket 1 moves in the axial direction toward the open discharge endthereof, an annular free space will be formed between the pusher bottom8 and the layer of centrifuged solids previously advanced by the pusherbottom, so that additional material to be centrifuged can enter thisannular free space from the feed funnel 7. Thus, as the basket 1 isaxially reciprocated and the pusher bottom 8 is held against axialreciprocation, the latter will act to progressively feed the centrifugedsolids toward the dischargeend of the basket.

Although the centrifuge illustrated in FIG. 1 has a side wall 2 which iscylindrical, that is, of equal diameter along its entire length, it willbe understood that such cylindrical configuration of the side wall ofthe basket is necessary only in that portion of the latter accommodatingthe pusher bottom 8, and that the remainder of the basket extending fromthe vicinity of the pusher bottom to the open discharge end may be givena conical configuration so that the basket increases in diameter towardits open discharge end and a component of the centrifical force will beavailable to act upon the centrifuged solids in the direction along theconical wall surface, thereby to assist in the movement of thecentrifuged solids toward the open discharge end.

Further, it will be apparent that, in the embodiment of the inventiondescribed above with reference to FIG. 1, the relative reciprocation ofthe pusher bottom 8 and basket 1 has a stroke equal to the reciprocatingstroke of the basket 1. However, the pusher bottom may be also axiallyreciprocated relative to the centrifuge housing, but with the directionof the reciprocating movement of the pusher bottom being always opposedto the direction of reciprocating movement of the centrifuge basket,thereby to increase the length of the stroke of the relativereciprocation of the pusher bottom and basket for correspondinglyincreasing the rate at which the pusher bottom is effective to dischargecentrifuged solids from the basket. Such an arrangement is illustratedin FIG. 2, wherein the centrifuge basket 1a is mounted on a shaft 17awhich is carried by a bearing 20a in a partition 21a of the centrifugehousing 4a so that the centrifuge basket is free to be rotated about itscentral axis (by means not shown in the drawing) and also to be axiallyreciprocated by a conventional electromagnetic oscillator 23 connectedto the shaft 17a. As in the centrifuge of FIG. 1, the centrifuge of FIG.2 is provided with a circular pusher bottom 8a fitting closely withinthe basket 1a and carried by a shaft 9a having an end portion 14a ofnon-circular cross-section slidably received in a recess 18a having amating cross-section and formed in the adjacent end of shaft 17a to openthrough the end wall 15a of the basket, so that the pusher bottom 8a isrotated with the basket and is independent of the axial reciprocation ofthe latter. As distinguished from the first described embodiment of theinvention, in the centrifuge of FIG. 2, the end of the shaft 9aextending through the open end of the centrifuge basket is rotatablymounted in a bearing 13:: carried by the housing 4a, and such bearing13a merely gives radial support to the shaft 911 which is free toreciprocate axially relative to the housing. Further, the end of shaft9a extending out of housing 4a is equipped with an independentelectromagnetic oscillator 24 which effects axial reciprocation of theshaft 9a and which, as diagrammatically illustrated in FIG. 2, isconnected to the same source of electric current as the oscillator 23.The two oscillators 23 and 24 are arranged so that the correspondingshafts 17a and 9a are always moving in opposite directions. If theoscillators 23 and 24 are of identical design, the reciprocating strokeof the pusher bottom 8a will be equal, in length, to the reciprocatingstroke of the basket la, so that the length of the stroke of therelative reciprocation, which determines the rate at which the pusherbottom 8a effects discharge of the centrifuged solids from the basket1a, will be twice that obtained with the arrangement of FIG. 1. r r rAlthough FIG. 2 does. not. illustrate any means for feeding material tobe centrifuged into the basket 1a, it is to be understood that a feedingmeans similar to that described with reference to the embodiment of FIG.1 may also be employed in connection with the embodiment of theinvention illustrated in'FIG. 2.

Referring now to'FIG. 3, it will be seen that the vibratory. centrifugethere illustrated is of the kind operated-by a dual-mass oscillatingsystem, for example, as disclosedin the afore-mentioned US. Patent2,872,045 toThomas Wirth, Karl-Heinz Nebhuth and Karl Wenger. In thecentrifuge of FIG. 3, the centrifuge basket 1b having a: cylindricalperforated side wall is once again mounted withv its axis extendinghorizontally within a centrifuge housing 4b. The shaft 17b having thebasket 1b securely connected to one end thereof is hollow and isslidably received within, an elongated sleeve 26 which is rotatablysupported, adjacent its opposite ends, by ball bearings 27 and 29respectively carried by transverse walls or partitions'28 and .30 of thehousing 4b. The end of the elongatedsleeve ,26 remote from thecentrifuge basket projects from the housing 45 through the transversewall 28 and carries a drive pulley 31 which is operatively connectedwith a pulley 33 by means of V-belts 32. The pulley 33 is mounted on theshaft of an electric motor 34 to be driven by the latter.

The elongated sleeve 26 has two elongated slots 35 and 36. which extendaxially and are axially spaced apart at locations between the bearings27 and 29. A collar 37 is slidably mounted on the sleeve 26 in theregion of the slot 35, and the collar 37 is securely connected to thebasketshaft 17b by means of a screw 38 which extends through the slot 35and is free to move axially in the latter. The other slot 36 of thesleeve 26 registers with a slot 39 provided, in thehollow basket shaft17, and a wedge or key member 40 passes slidably through the registeririg slot 36 and opening 39 to connect a balancing mass member 41,which is slidable upon the sleeve 26, to a connecting rod 42 which isaxially slidable within the hollow shaft 17b and which forms an axialextension of the shaft 9b carrying a pusher bottom 8b within thecentrifuge basket 1b. Both the hollow basket shaft 17b and theconnecting rod 42 project axially beyond the end of the sleeve 26 whichcarries the drive pulley 31 for connection to a hydraulic oscillator 43.The oscillator 43 includes a piston 45 which is connected to the end ofthe connecting rod 42 and is slidably arranged in a cylinder 44connected tothe shaft 17b, The cylinder44 is, in turn, slidable within aguide housing 46 which has two pressure fluid supply lines 47 and 48connected thereto and opening into annular channels or grooves 49 and 50formed in the inner surface of the guide housing. Further, the cylinder44 is provided with radial openings 49a and 50;: positioned .for,registration with the annular grooves 49 and50,respec'tively. Theopenings 49a and 50a communicate with the interior spaces 51 and 52,respectiv'ely, within the cylinder 44 at theopposite sides of piston'45. The lines or conduits 47 and 48 are alternately connected to asource of fluid under pressure by a suitable valve arrangementv (notshown). Thus, when fluid under pressure is supplied tothe space 51through the line 47, groove 49 and opening 49a, the piston 45, and hencethe "connecting rod 42, shaft 9b, pusher bottom 8b, and balancing'massmember 4 1, are all displaced axially toward the left, as viewedin FIG.3, while the cylinder, and hence, the shaft ;17b and the basket 1b, areall displaced toward theright, as viewed in FIG. 3. On the other hand,when fluid under pressure is supplied to the space 52 through the lineor conduit 48, groove 50, and opening 50a, the piston 45, connecting rod42, shaft 9b, pusher bottom 8b and balancing mass member 41 aredisplaced. axially toward the right, while cylinder 44, shaft 17b, andbasket lb areall displaced axially toward the left. I

,1 Further, in theerrangement ofFIG. 3, thrust washers 53 and 54aremounted onthe sleeve 26 against the .6011- fronting faces of ballbearings 27 and 29, respectively, and helical springs'55 and 56extending around the sleeve 26 are axially interposed between the thrustwasher-53 and the balancing mass member 41, and between thrust washer 54and the collar 37, respectively. Finally, an additional helical spring57, which extends around the sleeve 26, is axially interposed betweenthe collar 37 and-the balancing mass member 41 to form a resilientcoupling between the balancing mass member and the basketlb' carried bythe shaft 17b to which the collar 37; is fixedly attached.

In the above described arrangement, theelastically or resilientlycoupled basket 1b and balancing mass member 41 provide a dual-massoscillating system, with the pusher bottom 8b which isconnected to themember 41 by way of the shaft 9b and the key 40, forming part of thebalancing mass. With the mass of the basket 1b and, the balancing massbeing properly adjusted relative to each other, a pressure impulseoccurring in cylinder 44' causes simultaneous axial oscillations orfreciprocations of the mass of the basket and of the balancing mass inopposite directions, and the springs 55 and 5 6 serve to' transmitopposed reactions to the reciprocations'to'the housing 4b,

so that neither the housing 4b nor the rotary drive, isinfluenced by, orsubjected'to, the "axial vibrations of the centrifuge basket and of thebala'ncing'mass.

In the embodiment of FIG. 3, the pusher bot-tom 8b operates in the samemanner as in'the embodiment described With reference to FIG. 2, but itis not connected to a separate .osci-llator. Since the pusher bottom 8band the basket 1b always move in opposed directions relative to thehousing 4b, it is apparent that the length of stroke of thereciprocation of the pusher bottom relative to the basket is twice thelength of stroke of the'basket alone, thereby to provide a relativelyhigh rate of discharge of the centrifuged solids.

Although each of the embodiments of the invention described withreference to FIGS. 1, 2 land 3, respectively, includes a pusher bottomadjacent the closed end of the centrifuge basket and reciprocatedaxially relativeto the latter to progressively. move the centrifugedsolids toward the open end of the basket, by contact with thecentrifuged solids only at a location adjacent the closed end of thebasket, it is to be noted that, in accordance with this invention,arrangements may be provided within the basket for imparting additionalimpulses to the centrifuged solids as the latter move along the basketwall toward the open discharge end of-the basket. Thus, the presentinvention may be applied to centrifuge baskets of the kind which areenlarged stepwise towards the discharge end thereof, for example, asused in centrifuging materials, such as, sugar products, which aredifficult to filtrate. Because of the great length of these baskets, thecentrifuged material or solids is compressed while being fed toward thedischarge end of the basket, so that the friction between the materialand the basket wall is increased, and a single pusher bottom, as in theembodiments of FIGS. 1, 2. and 3, is no longer capable of providingadequate thrust for advancing the centrifuged material. Accordingly,referring to FIG. 4, it will be seen that, in the embodiment of theinvention there illustrated, the centrifugebasket, generally identifiedat 10 has a side wall made up of perfo rated cylindrical portions 58a,58b, 58c and 58d of progressively increasing diameter.

The successive cylindrical sections or portionsof the side wall of thecentrifuge have their adjacent ends disposed in axially overlappingrelationship, while the ends of the sections 58b, 58c and 58d facingtoward the small diameter end .of the basket are provided with radiallyinward directed annular flanges 59a, 59b and 590, respectively, whichconnect to the sections 58a, 58b and 580, respectively, in order todefine annular spaces 60a, 69b and 600, respectively, betweentheoverlapping end portions of the cylindrical wall sections, with suchan- 7 nular spaces opening axially in the direction toward therelatively large diameter discharge end of the basket.

The'basket 1c has a pusher bottom 8c supported axially Within theportion of the basket defined by the wall section 58a of smallestdiameter, while additional pusher rings 61a, 61b and 610 are slidablydisposed in the annular spaces 60a, 60b and 600, respectively, and closethe open ends of such spaces. Thus, in effect, each of the pusher ringsforms an axially movable flange at the end of the related section 58a,58b or 58c which extends in the direction toward the open end of thebasket.

The basket 10 is mounted on a hollow shaft 170 by way of an annularflange 65 extending from the latter and secured to rods or straps 66whichextend axially from the wall section 58a of the basket. Further,the pusher bottom 8c is carried by a shaft 64 which is integral with aconnecting rod 420, and a disc 63 is mountedon the shaft 64 between thepusher bottom 8c and the flange 65. The pusher rings 61a, 61b and 61care connected to'the disc 63 by rods 62 so that the pusher rings willreciprocate axially with the pusher bottom 80 relative to the basket 10.

In the embodiment of FIG. 4, the hollow shaft 17c and the connecting rod42c correspond to the hollow shaft 17b and the connecting. rod 42,respectively, of the embodiment of the invention previously describedwith reference to FIG. 3', and, a dual-mass oscillating system may besimilarly provided for effecting axial reciproca tion of the basket 10and of the pusher bottom 80 and the associated pusher rings in opposeddirections.

As in the previously described embodiments, the material to becentrifuged is supplied to the basket 10 by way of a feed pipe 5c and afunnel 70 opening within the relatively small diameter end portion ofthe basket so that the material to be centrifuged is discharged againstthe pusher bottom 8c.- As in the embodiments of the invention describedwith reference to FIGS. 1, 2 and 3, the relative reciprocation of thepusher bottom 8c and of the basket 1c cause the pusher bottom toprogressively propel 'the centrifuged solids along the wall section 58ain the direction toward the relatively large diameter open end of thebasket. However, in the embodiment of FIG. 4, the pusher rings 61a, 61band 61c, which reciprocate with the pusher bottom, provide additionalimpulses for moving the centrifuged solids toward the open end of thebasket 1d includes frusto-conical, perforated wall sections 58a, 58a and58 with the adjacent ends of such sections being joined together bystructures 59d and 59e which define annular spaces 60d and 60e,respectively,

opening axially in the direction toward the relatively large dischargeend of the basket and having cylindrical inner and outer surfaces.Pusher rings 61d and 61e are axially slidable within the annular spaces60d and 60a, respectively, and are connected, by rods 62d, to the disc63d.carried by the shaft 64d which supports the pusher bottom 8d withinacylindrical extensiouat the small diameter end of the wall section 58d.As in-theembodiment'of the invention illustrated in FIG. 4, the basket1d is secured to a flange 65d on the hollow shaft 17d by straps or rods66d which extend 'slidably through suitable openings in the disc 63d,while the shaft 64d is integral with a connecting rod 42d, so thattheconnecting rod 42d and the hollow shaft 17d may be oppositelyreciprocated, for example, by the dual-mass oscillating system of FIG.3, in order to provide for the opposite reciprocation of the pusherbottom and pusher rings, on the one hand, and the basket 1d on'the otherhand. Thus, when material to be centrifuged is supplied to therelatively small diameter end of the basket 1d by way of a feed pipe 5dand feeding funnel 7d, the reciprocated pusher bottom 8d causes initialmovement of thecentrifuged solids along the wall section 58d.Thereafter, the reciprocated pusher rings 61d and 61e provide additionalimpulses for continuing the movement of the centrifuged solids along thesuccessive wall sections 584; and 58 Since the wall sections 58d, 58eand 58f are frusto-conical,. the 'centrifical forces acting uponcentrifuged solids lying against such wall sections will have componentsacting along the wall sections in the direction toward the opendischarge end of the centrifuge basket, thereby to assist or promote themovement of the centrifuged solids toward the open discharge end of thebasket.

The above described embodiments of the invention all serve to ensure thecontrolled discharge of the centrifuged solids while avoiding damage tothe granular structure of the latter. During the movement of thecentrifuge basket in the axial direction opposed to the dischargemovement of the solids deposited against the basket wall, such solidsabut against either the pusher bottom alone, as in FIGS. 1, 2 and 3, oragainst the pusher bottom and the associated pusher rings, as in FIGS. 4and 5, so that the deposited centrifuged solids are given a well definedimpulse toward the discharge end of the basket. This permits thedischarge of the centrifuged solids even from a cylindrical basket, asin FIGS. 1, 2 and 3, and improves the efliciency of the dischargemovement in a basket having a frusto-conical wall, for example, as shownin FIG. 5. ..Fu.rther, the devices embodying the invention ensureuniform, practically continuous and adjustable movement of thecentrifuged solids toward the discharge end of the basket, thereby toresult in uniform dewatering of the material. The rate of movement ofthe centrifuged material through the basket, and therefore the capacityof the vibratory centrifuge embodying the invention can be increased, ifnecessary, to approximately twice the usual corresponding rates, byproviding an oscillatory drive for the pusher bottom as well as for thebasket, for example, as in the embodiments of FIGS. 2, 3, 4 and 5;

It should be understood that the basket of the centrifuge of ourinvention vibrates or oscillates at a relatively very high frequency.The frequency of the vibratory or oscillatory motions is approximately1800 per minute, and the amplitude is about 10 to 1?. mm. Asdistinguished from such motions, pusher bottoms, so far as they havebeen already used in centrifuges, operate through a stroke of 35 to 65mm. at strokes per minute. While these known pusher bottoms pushcentrifuged goods forcibly forward and out and largely destroy thegranular structure of the material being centrifuged, any rubbing oflfby friction and loss of luster is eliminated when working with ourvibratory centrifuge, which improves the quality of the centrifugedsolids. In our centrifuge, the material is only shaken to cause thelatter to slide along the basket walls. Our centrifuge is thusparticularly suitable for the separation of crystalline materials, suchas sugar, salt, and the like.

Although illustrative embodiments of the invention have been describedin detail herein with reference to the drawings, it is to be understoodthat the invention is not limited to those precise embodiments, and thatvarious changes and modifications may be effected therein withoutdeparting from the scope or spirit of the inven tion, except as definedin the appended claims.

What is claimed is:

1. In a vibratory centrifuge; the combination of a housing, a basket insaid housing opening axially at one end for discharge of centrifugedsolids through the latter and having a wall which is cylindrical atleast in a portion of the basket adjacent the opposite end of thelatter, means supporting said basket for rotation, a pusher bottomwithin said portion of the basket, means supporting said pusher bottomwithin the basket for rotation with the latter, and means effective tocause relative axial reciprocation of said pusher bottom and basketthrough a stroke having a minimum length equal to the length of thereciprocating stroke of said basket and a maximum length ofapproximately twice said length of the reciprocating stroke of thebasket, with said means eifective to cause relative reciprocation, beingalso effective to axially reciprocate said basket at a frequency of theorder of 1800 cycles per minute and through a stroke of approximately to12 millimeters, so that, when material to be centrifuged is fed to saidbasket at the side of said pusher bottom facing toward said one end ofthe basket, the solids in the material collect on said Wall of thebasket and are progressively displaced towards said one open end fordischarge from the basket by said pusher bottom in response to therelative reciprocation of said basket and pusher bottom.

2. In a vibratory centrifuge; the combination as in claim 1, whereinsaid means efiective to cause relative axial reciprocation of saidpush-er bottom and basket includes means for axially reciprocating saidbasket and means for axially reciprocating said pusher bottom with thedirection of axial movement of the latter being always opposed to thedirection of axial movement of said basket.

3.In a vibratory centrifuge; the combination as in claim 1, furthercomprising means for axially reciprocating said basket, said means foraxially reciprocating said basket including a balancing mass memberreciprocable in the direction of the axis of said basket, means forreciprocating said balancing mass member in opposition to thereciprocation of said basket, and means elastically coupling saidbalancing mass member to said basket so that said basket and balancingmass member form a dualmass oscillating system, and wherein said meanseffective to cause relative reciprocation of said pusher bottom andbasket includes rigid connecting means between said balancing massmember and said pusher bottom so that the latter reciprocates with saidbalancing mass member relative to said basket.

4. In a vibratory centrifuge; the combination as in claim 1, whereinsaid wall of the basket is cylindrical throughout the length of thelatter.

5. In a vibratory centrifuge; the combination as in claim 1, whereinsaid wall of the basket further includes a frusto-conical portionextending from said cylindrical portion and increasing in diameter inthe axial direction toward said one open" end of the basket so that acomponent of centrifugal forces acting on centrifuged solids collectedon said wall exists along said frusto-conical portion to assist saidpusher bottom in displacing the centrifuged solids toward said one openend.

6. In a vibratory centrifuge; the combination as in claim 1, whereinsaid wall of the basket increases in diameter from said cylindricalportion toward said one open end of the basket and further has at leastone annular space opening axially toward said one end be tween inner andouter cylindrical surfaces at a location intermediate said cylindricalportion of the wall and said one end, and further comprising a pusherring axially slidable in each annular space and means connecting saidpusher ring to said pusher bottom for reciprocation with the latterrelative to said basket, whereby each pusher ring further displaces thecentrifuged solids along said wall toward said one open end of thebasket in response to relative reciprocation of said basket and saidpusher bottom and ring.

7. In a vibratory centrifuge; the combination as in claim 6, whereinsaid wall has at least one additional cylindrical portion with adiameter larger than that of the first mentioned cylindrical portion andextending from the latter in the direction toward said one open end,said first and additional cylindrical portions having axiallyoverlapping end portions, and said annular space is defined between saidaxially overlapping end portions with said pusher ring forming a radialshoulder between said first cylindrical portion and said additionalcylindrical portion.

8. In a vibratory centrifuge; the combination as in claim 6, whereinsaid wall has a frusto-conical portion extending from said cylindricalportion, and increasing in diameter, toward said one open end of thebasket, and said annular space is located intermediate the opposite endsof said frusto-conical portion so that the displacement of thecentrifuged solids along said frusto-conical portion of the Wall by saidpusher bottom and pusher ring is further assisted by a component of thecentrifugal forces.

References Cited in the file of this patent UNITED STATES PATENTS2,685,370 Ruegg Aug. 3, 1954 2,755,934 Ruegg July 24, 1956 2,782,930Heckmann Feb. 26, 1957 2,861,691 Linke et a1. Nov. 25, 1958

